Automatic pool cleaning devices are generally well known in the art for removing debris from swimming pools and reducing or eliminating the need for manual vacuuming. Many swimming pools include a water filtration system with a pump for drawing or suctioning water from the pool and circulating it through the system. The filter system may include a relatively large-pored filter basket for trapping debris such as leaves and twigs and a filter canister containing a filter media for trapping smaller particles including sand and silt. From the filter canister, the water is recirculated to the pool via one or more return lines.
Such filtration systems may be operated for several hours at a time on a daily basis and, in combination with traditional chemical treatments such as chlorination or the like, help keep the pool water clean. However, such water filtration systems are not particularly effective at removing debris that settles on the bottom or sides of the pool. In the past, settled debris has typically been removed by coupling a vacuum hose to the suction side of the pool water filtration system, to a skimmer well located near the water surface at one side of the pool for example, and then manually moving a vacuum head coupled to the hose over the submerged pool surfaces to vacuum settled debris directly to the filter canister where it is collected and separated from the pool water. However, manual vacuuming of a swimming pool is a labor intensive task that takes time away from enjoying the use of a swimming pool.
Many automatic pool vacuum systems have been developed over the years. Such systems may be powered by a pump pumping water to the cleaner, which systems use the venturi effect to draw dirt into the cleaner, or by the pool's skimmer system which draws water into and through the cleaner. In either case, the moving water may be used to power a turbine or similar device to convert the movement of the fluid into mechanical energy for driving the wheels and moving the cleaner in a more or less random pattern along the pool bottom. Alternately, the pool cleaner could be propelled by jetting fluid from the housing or by an electric motor.
FIGS. 9 and 10 illustrate, somewhat schematically, a conventional automatic pool cleaner that includes a housing 200 having a front 202, a rear 204 and a bottom 206. A front wheel 208 and a pair of rear wheels 210 support housing 200 for movement along the bottom 212 of a pool. A vacuum hose 214 connects the pool cleaner to a pool skimmer (not illustrated), and suction from the pool skimmer draws dirt and debris through suction inlet 216 and passage 218 to vacuum hose 214 and into the pool's filtration system (not illustrated). A second passage 220 connects a fluid drive mechanism 222 to vacuum hose 214 so that fluid drawn through drive mechanism 222 by the pool's filtration system turns a first gear 224 connected to a second gear 226 on rear wheel 210 to move the pool cleaner along the bottom 212 of the pool. Many other types of conventional automatic pool cleaners and propulsion systems are also known.
Vacuuming a pool, however, does not substantially affect algae and bacteria that can grow on pool surfaces. This is due in part to the fact that the bacteria adheres to the surfaces too tightly to be vacuumed off and partly due to the protective membrane that coats many types of bacteria and algae. To remove such material, it may be necessary to periodically manually scrub the bottom and sides of the pool, or to use high concentrations of chemicals to kill the algae.
Pool cleaners having motor driven brushes, such as disclosed in U.S. Pat. No. 4,154,680 to Sommer, for example, are known and may be generally effective for algae removal. However, the use of a motor to drive a brush adds to the cost and complexity of pool cleaners. It would therefore be desirable to provide a vacuum type automatic pool cleaner that provides benefits similar to those provide by more complex automatic cleaners having scrubbing brushes without the added cost and complexity of a motor driven scrubbing system.